Nautical engineers have long dreamed of a craft that could race across wave tops like a speedboat and seconds later dive beneath them like a submarine. But crossing the two breeds presents a catch-22: Subs need heft to sink, but speedboats need to be lightweight to go fast. With an investment of nearly $2 million and years of research, former auto-shop owner Reynolds Marion of Lake City, Florida, has finally hit on a solution, a machine he’s dubbed the Hyper-Submersible Powerboat. When complete, it will reach speeds of up to 45 mph and dive down to 1,200 feet.